The present invention relates to the separation of oily and solid matter from oil-water emulsions. Oil-water emulsions are defined as emulsions containing water and oily materials including oils, greases, fats, fatty materials and the like from animal, vegetable or petroleum sources. Oil-in-water and water-in-oil emulsions are included.
Many industrial and agricultural processes produce oil-water emulsions containing various waste materials such as oils, greases, fats, insoluble organic and inorganic solids and water soluble salts. In many instances, these materials, which may be of substantial value, remain unused due to the fact that they are either unrecoverable or that it is economically unfeasible to do so. Exemplary of some of these oil-water emulsions are water-oil emulsions which occur as undesirable by-products of petroleum refining and waste emulsions containing animal or vegetable fats, grease, oils and/or other related oily substances, such as packing plant waste emulsions, fish processing waste emulsions, steel mill waste emulsions and wool scouring emulsions.
The cost of treatment of oil emulsions by known processes, such as those processes which rely on acid or base treatment or solvent extraction, is quite high and in general has not proved economically attractive. However, the discarding of valuable and useable materials often found in these oil emulsions is an unfortunate waste, and in most cases, the disposal of the emulsions to sewage systems and/or streams and rivers is environmentally unacceptable without treatment of some sort, e.g., by subjecting them to biodegradation for prolonged periods in storage lagoons.
A particular example of this type of situation is the disposal problem encountered with oil emulsions resulting from the wool scouring process. As pointed out in United States Patent to Joseph Del Pico, U.S. Pat. No. 3,848,804, incorporated by reference herein, wool scouring emulsion contains a substantial amount of wool grease as well as other impurities, such as suint, dung, earth, sand, etc.. The wool scouring emulsion is typically formed by washing of the wool in either a cold water bath to remove water soluble impurities or a hot water surfactant-containing bath which emulsifies and removes the wool grease. This wool scouring emulsion will usually contain from 1 to 8% wool grease which is composed mainly of lanolin. A centrifugal recovery process which has been used prior to the present process is said to provide for recovery of only up to about 50% by weight of the wool grease of the emulsion and typically 25 to 40%.
Another method of wool grease recovery from wool scouring emulsions is known as the acid cracking process, where the pH is adjusted to between about 2 and 4 to provide for destabilization of the wool grease emulsion, followed by subsequent collection of the wool grease as a sludge material. A typical recovery yield of wool grease using this process is about 65% by weight, however, in most cases this treatment deleteriously affects the mixture of alcohol, acid and ester compounds of which lanolin is composed and thus has the inherent disadvantage of recovering a low quality lanolin.
In some instances, wool scouring emulsion is processed by a combination of the above described leading methods as well as other treatments such as, for example, hexane extraction, however, it has been found that while increasing the yield of wool grease, combinations of these processes become increasingly more expensive.
There are many other instances in which oil-water emulsions contain an economically valuable material, which is undesirable to dispose of by dumping into the sewage systems, and economically unfeasible to remove by prior art means.
A method for dewatering sludges by use of an amine or mixture of amines having an inverse critical solution point is described and claimed in Emanual Pat. No. 3,899,419 issued Aug. 12, 1975 and assigned to the assignee hereof, and expressly incorporated herein by reference. Improvements in such process are disclosed in the aforementioned, commonly assigned, co-pending applications of Ames, U.S. Pat. No. 385,489, and Peters, U.S. Pat. No. 385,488.
It has now been found that the amines of these processes provide a novel and economical method of processing a variety of oil-water emulsions, which may or may not contain insoluble solids but which contain oily or otherwise hydrophobic material having substantial solubility in the amine or amine mixture.
It is therefore an object of the present invention to provide a method of processing oil-water emulsions whereby oily or other hydrophobic materials may be removed therefrom and otherwise separated from salts and other hydrophilic materials.
It is a further object of the present invention to provide a method for processing an oil-water emulsion which is simple and economical, and provides for substantially complete removal of such oily materials from oil-water emulsions.
It is an additional object of the present invention to provide a method of processing an oil-water emulsion whereby economically valuable materials may be removed from such oil emulsions without degrading their quality, and in a yield greater than has been economically feasible in the prior art.
It is a further object of the present invention to efficiently separate solid matter from oil emulsions.
It is furthermore a particular object of the present invention to provide a method for the processing of a wool scouring emulsion to economically recover valuable by-products therefrom such as, for example, lanolin, and to provide for the environmentally safe disposal of unwanted by-products.